||For the delivery of new ACS IMPHTTABs, WFC3 IMPHTTABs, and the initial delivery of WFC3 delta-flat reference files.
||The reason is the deliveries of a new COS NUV flat and updated COS flatfile rmap.
||These new Pflats were computed by stacking deep exposures of sparse fields with sources masked over the WFC3 lifetime. They replace the prior set of reference files, which were based on the original ground flats, multiplied by a grey sky flat correction from inflight data through 2010. The new sky flats correct for wavelength-dependent residuals of plus or minus 0.5 percent at the center of the detector and 1-2 percent at the detector edges, with Poisson errors about 0.2 percent or better. For details, see Mack et al. 2020, WFC3 ISR in prep., WFC3/IR Filter-Dependent Sky Flats. An accompanying set of delta Dflats corrects for 148 known IR blobs in six filters as a function of date. These were computed by
stacking the sky flat observations after the appearance of each blob and correct for losses as large as about 30 percent at the blob center with less than 1 percent errors. For details, see Olszewski et al. 2020, WFC3 ISR in prep., WFC3/IR Blob Flats.
||These WFC3 UVIS superdarks, drk, and CTE corrected superdarks, dkc, will affect all UVIS data taken from September 3rd through September 29th 2020. Currently, the automated calibration pipeline and Calibration Reference Data System only have WFC3 UVIS drk and dkc reference files up to a USEAFTER date of August 31st 2020. The automated pipeline should now use these reference files to perform dark subtraction on any UVIS datasets obtained between the dates above because they represent the most accurate estimate of the dark current and hot pixels at the time of the science observation. These WFC3 UVIS drk and dkc files were generated using dark exposures from the HST Cycle 27 daily monitoring program 15716. More information regarding the method used to create UVIS dark calibration reference files can be found in WFC3 ISR 2016 08. Additionally, the header of each reference file has a detailed history section outlining the process and provides a list of datasets used to create each file.